Buggy code:
public class RedirectView extends AbstractUrlBasedView implements SmartView { private static final Pattern URI_TEMPLATE_VARIABLE_PATTERN = Pattern . compile ( "\\{([^//]+?)\\}" ) ; private boolean contextRelative = false ; private boolean http10Compatible = true ; private boolean exposeModelAttributes = true ; private String encodingScheme ; private HttpStatus statusCode ; private boolean expandUriTemplateVariables = true ; public RedirectView ( ) { } public RedirectView ( String url ) { } public RedirectView ( String url , boolean contextRelative ) { } public RedirectView ( String url , boolean contextRelative , boolean http10Compatible ) { } public RedirectView ( String url , boolean contextRelative , boolean http10Compatible , boolean exposeModelAttributes ) { } public void setContextRelative ( boolean contextRelative ) { } public void setHttp10Compatible ( boolean http10Compatible ) { } public void setExposeModelAttributes ( final boolean exposeModelAttributes ) { } public void setEncodingScheme ( String encodingScheme ) { } public void setStatusCode ( HttpStatus statusCode ) { } public void setExpandUriTemplateVariables ( boolean expandUriTemplateVariables ) { } public boolean isRedirectView ( ) { } @ Override protected boolean isContextRequired ( ) { } @ Override protected void renderMergedOutputModel ( Map < String , Object > model , HttpServletRequest request , HttpServletResponse response ) throws IOException { String targetUrl = createTargetUrl ( model , request ) ; targetUrl = updateTargetUrl ( targetUrl , model , request , response ) ; FlashMap flashMap = RequestContextUtils . getOutputFlashMap ( request ) ; if ( ! ( CollectionUtils . isEmpty ( flashMap ) ) ) { UriComponents uriComponents = UriComponentsBuilder . fromUriString ( targetUrl ) . build ( ) ; flashMap . setTargetRequestPath ( uriComponents . getPath ( ) ) ; flashMap . addTargetRequestParams ( uriComponents . getQueryParams ( ) ) ; } FlashMapManager flashMapManager = RequestContextUtils . getFlashMapManager ( request ) ; <START_BUG> flashMapManager . save ( flashMap , request , response ) ; <END_BUG> sendRedirect ( request , response , targetUrl . toString ( ) , this . http10Compatible ) ; } protected final String createTargetUrl ( Map < String , Object > model , HttpServletRequest request ) throws UnsupportedEncodingException { } protected StringBuilder replaceUriTemplateVariables ( String targetUrl , Map < String , Object > model , Map < String , String > currentUriVariables , String encodingScheme ) throws UnsupportedEncodingException { } @ SuppressWarnings ( "unchecked" ) private Map < String , String > getCurrentRequestUriVariables ( HttpServletRequest request ) { } protected void appendQueryProperties ( StringBuilder targetUrl , Map < String , Object > model , String encodingScheme ) throws UnsupportedEncodingException { } protected Map < String , Object > queryProperties ( Map < String , Object > model ) { } protected boolean isEligibleProperty ( String key , Object value ) { } protected boolean isEligibleValue ( Object value ) { } protected String urlEncode ( String input , String encodingScheme ) throws UnsupportedEncodingException { } protected String updateTargetUrl ( String targetUrl , Map < String , Object > model , HttpServletRequest request , HttpServletResponse response ) { } protected void sendRedirect ( HttpServletRequest request , HttpServletResponse response , String targetUrl , boolean http10Compatible ) throws IOException { } protected HttpStatus getHttp11StatusCode ( HttpServletRequest request , HttpServletResponse response , String targetUrl ) { } }

Fix:
flashMapManager . saveOutputFlashMap ( flashMap , request , response ) ;